Venipuncture is the process of inserting a needle into a vein to withdraw blood or start an intravenous line for giving medications and fluid. Generally, veins in the back of the hand, forearm or anticubital space, or bend of the elbow, are used for venipuncture. Less commonly, veins in the leg or side of the neck may be used. Venipuncture is a learned skill that requires practice to become proficient and comfortable with the technique.
Gloves
The health care professional puts on gloves before she begins working with a patient. This helps protect her from being contaminated by diseases in a patient's blood. It also keeps the patient safe from contamination by the professional.
Preparation
Preparing a patient for venipuncture is important to prevent patient injury and infection. A patient should be seated before venipuncture, as fainting or dizziness can occur in people sensitive to having blood taken. Tight or constricting clothing or jewelry is removed from the area chosen for venipuncture, such as an arm.
The phlebotomist or nurse selects the most appropriate vein for blood collection. Skin over the vein is then cleansed. The University of Arkansas for Medical Sciences suggests cleansing skin over and around the vein with a 70% alcohol wipe in a spiral motion from the inside out.
Vein Puncture
A tourniquet is applied three to four inches above the chosen vein in an extremity, according to Kathryn A. Kalanick in her 2004 book Phlebotomy Technician Specialist: A Practical Guide to Phlebotomy. This allows blood to pool inside the vein for easier blood collection or insertion of an intravenous catheter. The patient may be asked to make a fist to further aid the pooling of blood.
The medical professional chooses a needle based on the patient's size, age and vein condition and purpose of the venipuncture. Needles have one side flattened into a point, called a bevel, which allows the needle to slide easily through the skin and into a vein. The needle is positioned with the bevel up, parallel to the vein at a 15-degree angle and is advanced into the vein in a quick, smooth motion.
Blood Collection
Once the needle is inside the vein, the professional can collect blood. Depending on the method of venipuncture used, she may attach a vacuum collection tube to the needle to collect blood or use a syringe. The desired amount of blood is collected in the tube of choice.
Intravenous Catheter Placement
An intravenous catheter, or IV, is left inside the vein to allow medication or fluids to be given directly into the bloodstream. IV needles are housed inside a flexible plastic sheath, called a catheter, which is attached to thin plastic tubing that connects to a medication bag. The catheter and needle are advanced into the vein as a unit. Once in place, the needle is withdrawn, leaving the catheter inside the vein. The catheter is taped securely in place before medications or fluids are given.
